The management of appropriate water levels in small bodies of water is normally accomplished via the use of water drainage structures, comprising: a baffle, riser, anchoring base, and discharge pipe.
These devices allow surface water to enter the drainage structure via the water surface and into the baffle and subsequently through the riser and out the discharge pipe. Often, the discharge pipe deposits the excess water through and onto the other side of an earthen dam system and into a drainage creek or wetland flood area.
The appropriate level of water in these systems is maintained by setting the riser at a predetermined height. The height of the riser determines the level at which surface water may enter the drainage structure.
The importance of maintaining the appropriate water level, via utilization of water drainage systems, is paramount for managing the water body for its intended use, i.e. flood control, water treatment, recreation, wetland management, agricultural resource utilization, etc.
For instance, in bodies of water small enough to be termed “ponds,” water depth affects: algae growth, aquifer contamination, water stratification, fish survival, sedimentation, and flood control. See, Cronk & Fennessy, Wetland Plants Biology and Ecology, Lewis Publishers. 2001; and also. Begon, et al., Ecology: Individuals, Populations, and Communities, Blackwell Scientific Publications, 2nd Edition, 1990, each of which are incorporated by reference herein in their entireties for all purposes.
For managing pond water levels for agriculture application, a water depth of at least six or seven feet is often needed to insure adequate water during dry periods. Further, to reduce widespread attached aquatic plant growth problems, a pond depth of at least four feet is often desired. This depth will generally prevent the growth of attached aquatic plants in clean ponds. Many emergent plants require water depths of less than six inches, while submerged plants typically require water one to two feet deep. Deep ponds will therefore restrict plant growth. A water depth of about six feet over the major portion of the pond will also increase winter survival of fish.
Despite the known importance of managing pond water depth, there remain significant obstacles that prevent land managers from appropriately controlling the depth of ponds. In particular, the clogging of water drainage systems by: (1) abiotic debris and (2) beaver (Castor sp.) infestation are two of the most pernicious problems faced by land managers attempting to maintain an appropriate and consistent pond water level.
To combat these two issues, land managers and engineers have developed elaborate surface water screening mechanisms that attempt to prevent abiotic debris congestion. For example, the structures represented by FIG. 10 are available in the industry and provide a physical barrier (i.e. debris grating) that is supposed to mitigate the effects of debris buildup. In theory, the surface water physical barrier provides enough distance between itself and the entrance into the riser that water is still able to freely flow through the riser and out through the drainage structure. However, these devices are often ineffective, as the buildup of debris becomes too large and dense to effectively allow the passage of water into the riser.
Also, the surface water devices aimed at preventing debris buildup from entering the water drainage system have little to no effect on the problems caused by beaver infestation.
Beavers are attracted to an area and stimulated to build dams by two main environmental cues: (1) active surface water current, and (2) the sound of falling or trickling water.
Beavers can detect surface water current flow and are attracted to active surface current. Thus, the typical water drainage systems utilized in the art, even if equipped with a surface water debris grate, or physical barrier, to prevent debris from clogging the riser, do not address the main attractant of the beaver, i.e. surface water movement. Rather, these structures can often exacerbate a beaver problem, by creating fast surface current flow.
A second stimulus that causes beavers to build dams and clog drainage systems is the sound of falling or trickling water, which are present with the drainage systems of the art.
Thus, the pond water control devices and drainage systems present in the art are ineffective in combating: (1) natural abiotic debris cloggage of the riser and also (2) biotic assisted cloggage of the riser caused by beaver dams.
The surface water inlets found in the drainage systems of the art are not only ineffective in ameliorating beaver infestations, but they are actually potent attractants of the beaver, as these structures create and amplify the sound of falling water and also create observable surface water movement.
An effective water management device is therefore drastically needed in the art to solve the problem of effective water level control that is not hampered by debris buildup and beaver infestations.